Process for recovering hydrocarbon

ABSTRACT

A process for recovering hydrocarbons from a subterranean hydrocarbon-bearing reservoir comprising: 
     contacting the reservoir with at least one plant derived aromatic containing component having ortho-quinone functionality in an amount effective to promote the chemical modification of at least one component of the hydrocarbons in the reservoir and optimally at least one additional oxidant in an amount effective to do at least one of the following: maintain at least partially the promoting activity of the plant derived aromatic component; produce at least a portion of plant derived aromatic component; and oxidize at least a portion of a component of the hydrocarbons, the contacting occurring at conditions effective to chemically modify the component of the hydrocarbons in the reservoir; and 
     recovering hydrocarbons from the reservoir.

BACKGROUND OF THE INVENTION

This invention relates to a process for recovering hydrocarbons, such aspetroleum and the like. More particularly, the invention relates toprocesses wherein hydrocarbons are recovered from subterraneanhydrocarbon-bearing formations, i.e., reservoirs.

Producing petroleum from subterranean reservoirs has become increasinglydifficult. A large portion of the original crude petroleum in place inmany subterranean hydrocarbon-bearing reservoirs remains in place afterprimary production and water flooding. As oil reserves dwindle andexploration for new discoveries becomes more difficult and costly, theuse of enhanced oil recovery (EOR) techniques on previously discoveredresources will play an increasingly important role in the overallproduction of crude petroleum.

One EOR technique which has been used involves surfactant injection.However, such surfactants are relatively costly and are not costeffective in producing increased quantities of hydrocarbon. A new EORprocess would be beneficial.

SUMMARY OF THE INVENTION

A new process for recovering hydrocarbons which involves modifying atleast one component of a hydrocarbon-based material has been discovered.This process provides an effective, convenient and economical approachto chemically modifying, preferably oxidizing, cracking, demetallizing,forming surfactants from, or altering the viscosity of or the like, oneor more components of a hydrocarbon-based material, preferablypetroleum.

One broad aspect of the present invention is directed to a process forrecovering hydrocarbons from a subterranean hydrocarbon-bearingreservoir. In one embodiment, the invention comprises contacting thereservoir with at least one plant derived aromatic component havingortho-quinone functionality at conditions effective to chemicallymodify, preferably oxidize, at least one component of the hydrocarbons nthe reservoir; and recovering hydrocarbons from the reservoir. The plantderived aromatic containing component is present in an amount effectiveto promote the chemical modification of the hydrocarbon component. Theplant derived aromatic containing component and mixtures thereof arepreferably substantially soluble at the conditions of use.

In another broad aspect, the present process comprises contacting asubterranean hydrocarbon-bearing reservoir with at least one plantderived aromatic containing component having ortho-quinone functionalityin an amount effective to promote the chemical modification of at leastone component of the hydrocarbons in the reservoir, and at least oneadditional oxidant at conditions effective to chemically modify one ormore of such components; and recovering hydrocarbons from the reservoir.The additional oxidant in these embodiments is preferably anoxygen-containing component, in an amount effective to do at least oneof the following: maintain at least partially the promoting activity ofthe plant derived aromatic containing component; produce at least aportion of the plant derived aromatic containing component complex; andoxidize at least a portion of the hydrocarbon in the reservoir. Thecontacting occurs in the presence of the additional oxidant atconditions effective to chemically modify the component of thehydrocarbons in the reservoir, and hydrocarbons are recovered from thereservoir.

The present process advantageously results in the chemical modificationof one or more components of the hydrocarbons in the subterraneanreservoir. Such chemical modification, preferably oxidation, of suchcomponent or components often results in enhanced recovery ofhydrocarbons, e.g., more efficient and/or higher effective hydrocarbonyields, from the reservoir. For example, the present contacting mayadvantageously result in the in situ generation of surfactants, whichsurfactants aid in releasing hydrocarbons from the non-hydrocarbon-basedportion of the subterranean reservoir, e.g., through emulsification,reduction of interfacial tension, and/or wetability changes, forexample, oil wet to water wet. Further, oxidative cracking and/oroxidative viscosity reduction of crude petroleum, for example heavycrude oil, tends to increase the mobility of the petroleum through thesubterranean reservoir, and to ultimately increase the recovery ofpetroleum. In certain aspects of this invention, oxidationemulsification can increase viscosity, thereby improving mobilitycontrol and better reservoir sweep efficiency for recovery of oil. Thepresent invention can provide a cost effective approach to the enhancedrecovery of hydrocarbons from subterranean reservoirs.

DETAILED DESCRIPTION OF THE INVENTION

The present process is effective to recover hydrocarbons from asubterranean hydrocarbon-bearing reservoir, preferably having at leastone injection means, e.g., an injection well, in fluid communicationwith at least one production means, e.g., a production well.

In one embodiment of the invention, the process comprises: contactingthe hydrocarbons in the reservoir with at least one plant derivedaromatic containing component in an amount effective to promote thechemical modification of at least one component of the hydrocarbons inthe reservoir and optionally at least one additional oxidant andmixtures thereof; and recovering hydrocarbons from the reservoir. In oneparticularly useful embodiment, the process comprises injecting into thereservoir, preferably through the injection means, one or more liquidcompositions or media, more preferably aqueous liquid media, includingone or more of the plant derived aromatic containing component describedabove; and recovering hydrocarbons from the reservoir, preferablythrough the production means. A drive fluid is preferably injected intothe reservoir, preferably through the injection means, to urgehydrocarbons in the reservoir toward the production means. This drivefluid may be separate and apart from the liquid medium described hereinas contacting the reservoir. However, it is preferred that the liquidmedium used to contact the reservoir also acts as a drive fluid, i.e.,to urge hydrocarbons in the reservoir toward the production means.

The present process has been found to provide for recovery ofhydrocarbons, e.g., crude petroleum, from subterraneanhydrocarbon-bearing reservoirs. This enhanced oil recovery or EORprocess is relatively inexpensive and cost effective for hydrocarbonrecovery. For example, the plant derived aromatic containing componentand oxidants, e.g., as described herein, which may be employed arerelatively inexpensive, available, and/or easy to produce.

The term "chemical modification" as used herein refers to a change inone or more of the components of the hydrocarbons in the subterraneanreservoir, which change preferably results from the chemical reaction,more preferably oxidation, of one or more of such components. In certaininstances, no specific chemical reaction can be pointed to account forthe change in the component or components. For example, the hydrocarbonsin the reservoir may become more easily emulsifiable, with water, as theresult of the present contacting. This improved emulsifiability is achemical modification as that term is used herein. Also, the chemicalmodification may occur with regard to the carbon and/or hydrogenportions of the hydrocarbons in the reservoir and/or to the otherportions, e.g., such as contained sulfur, nitrogen, oxygen, metals orthe like, of such hydrocarbons in the reservoir and/or acts to conditionor enhance rock wetability changes to water wet and/or acts to improvemobility control and sweep efficiency. The present contacting steppreferably produces surfactants in the reservoir and/or acts to reducethe viscosity of the hydrocarbons in the reservoir and/or acts tocondition or enhance rock wetability changes to water wet and/or acts toimprove mobility control sweep efficiency. The present contactingpreferably liberates at least a portion of the hydrocarbons in thereservoir. That is, an increased amount of hydrocarbons is preferablyrecovered from the reservoir using the present contacting step relativeto practicing a similar process without the present contacting step.

One embodiment of the present process involves contacting a subterraneanhydrocarbon-bearing reservoir with at least one plant derived aromaticcontaining component having ortho quinone functionality, preferablyselected from a component which has one or more water solubilizinggroups attached to the component more preferably as a water soluble saltsuch as an alkali metal salt. The plant derived aromatic containingcomponent having ortho-quinone functionality, hereinafter referred to asortho-quinone component, and mixtures thereof is present in an amounteffective to at least promote the chemical modification of thehydrocarbon material. The various embodiments of this invention can bepracticed singly or in any combination of embodiments, with selectionand optimization generally being a function of the crude oil type anddesired hydrocarbon recovered.

The benefits resulting from the process of this invention, e.g.,improved recovery of desired hydrocarbon and as a function of time, aresubstantial. Without wishing to limit the invention to any specifictheory of operation, it is believed that many of such benefits resultfrom the direct and/or indirect chemical modification, i.e., the effectof one or more of the above o-quinone containing components for exampleis an oxidation effect which promotes the recovery of hydrocarbons fromsuch reservoirs. It is believed that the o-quinone containing componentscan interact directly and/or indirectly with the hydrocarbons by forexample direct oxidation of the hydrocarbons and/or by the generation ofan active oxidant specie which interacts with the hydrocarbon materialto promote improved hydrocarbon recovery.

Another embodiment of this invention is the obtaining of such benefitsthrough a catalytic effect by the ortho-quinone containing components.Without wishing to limit the invention to any specific of operation, itis believed that the ortho-quinone containing component during itsinteraction with the hydrocarbon material is reduced and is subsequentlyregenerated by an additional oxidant such as an active oxygen specie,such as oxygen. During a given period of time in which the hydrocarbonis contacted with the ortho-quinone containing component and anadditional oxidant, the ortho-quinone containing component can cyclebetween an oxidized and reduced state, i.e., the component isregenerated, thereby allowing the chemical modification of thehydrocarbon material to be carried out with an amount of ortho-quinonecontaining component less than would be required without theregeneration of such component. The use of such lesser amounts of theortho-quinone containing component, i.e., a catalytic amount, allows forimproved process efficiencies.

The promoting effect of the presently useful ortho-quinone redox couplesallows the process to be effective, e.g., from the standpoint ofimproved recovery of desired hydrocarbon as a function of time, on awide variety of difficult to process reservoirs.

Improved yields or recoveries of hydrocarbons can often be achievedunder less severe and costly conditions by practicing the presentprocess, especially when compared to recovering hydrocarbon fromreservoirs without utilizing the process of this invention. The presentprocess is relatively easy to operate and control. Relatively lowconcentrations of the o-quinone containing components are used andrelatively mild process conditions may be employed. Thus, the presentinvention can provide a cost effective approach to hydrocarbon recoveryfrom reservoirs.

DETAILED DESCRIPTION OF THE INVENTION

The present process provides substantial advantages. For example, theuse of at least one of certain promoting o-quinone containingcomponents, particularly lignin and tannin derived componentsparticularly having water solubilizing groups such as the sodium saltand more particularly in a redox cycling catalytic amount in thepresence of an additional oxidant provides for improved contacting,e.g., to increase the rate of hydrocarbon material chemical modificationand ultimately to improve the yield of hydrocarbon recovered. Theimproved rate of hydrocarbon material chemical modification also resultsin significant process and cost economies. In addition, effectivehydrocarbon recoveries can be achieved utilizing crude oil, depleted,water flooded (heretofore difficult to process) crude oil.

The process of the present invention is useful for hydrocarbon recoveryfrom reservoirs, as defined herein. The present process employs at leastone of certain o-quinone containing components. Such components mayinclude alkali and/or alkaline earth metals and/or ammonium saltsprovided that they also contain o-quinone containing functionality whichis effective in the present invention. Such o-quinone containingcomponents are present during the contacting step in an amount effectiveto at least promote the chemical modification of the hydrocarbonmaterial in the crude oil. Thus, such ortho quinone containingcomponents are present in an amount effective to promote such chemicalmodification and/or to oxidize the hydrocarbon material in the crude oilto enhance and/or promote recovery.

The presently useful plant derived aromatic components having o-quinonefunctionality are preferably selected from the group consisting of oneor more lignin derived components, one or more tannin derived componentsand mixtures thereof. The lignin and tannin derived components may beselected from natural materials or lignin and tannin containingmaterials from various lignin and tannin manufacturing processes. As setforth above, preferred components having ortho-quinone functionality arethose that also have water solubilizing functionality particularly as awater solubilizing salt particularly at alkaline pH.

Lignin in higher plants is formed by complex enzymatic processes whichproduce substituted phenolic compounds. Lignin are a family ofthree-dimensional polymers which bind together the cellulose fibers inhigher plants. Lignin can provide rigidity to the plant structure and,being in general resistant to chemical and biological attack, helpsplants from decay. Lignin is distributed widely throughout the plantkingdom. Plant lignin are generally divided into three broad classeswhich are commonly called softwood, hardwood and grass or annual plantlignin. The latter also includes such plants as bamboo and palm. Thuslignin can be released by chemical or mechanical disintegration from awide variety of plant tissues including, as set forth above, softwood(coniferous), hardwood (deciduous) or from bark, cambium, sapwood orheartwood. In addition, lignin can be released from jute, rice hulls,peanut shells, barley, straw, begasse, coconut shells, alfalfa, pineneedles, oat and wheat straw, corn cobs and various other plantmaterials.

Although the exact structure of lignin is unknown, plant lignin fromcertain trees are considered to be a polymeric material almost entirelymade up of phenylpropane units that exist as branched chains ofcross-linked structures. In lignin from softwood trees, nearly all thearomatic rings have one methoxyl group in position three from the propylside chain.

The phenolic precursors of hardwood lignin trees contain methoxyl groupsin one or both of the positions adjacent to the phenolic hydroxyl;however, in softwoods the precursors are generally substituted at onlyone position and occasionally not at all. As a result of this softwoodlignin contains about twice as many reactive sites on the aromatic ringsand contain a higher proportion of carbon-carbon linkages betweenaromatic rings. A chemical structure which incorporates various chemicalgroupings found in, for example, spruce native lignin in their existingratios shows various joined coniferyl units with approximately one-thirdof the units still having a free phenolic group and most having analiphatic alcohol group in the side chain. A majority of the phenolicgroups are generally in etherified form, i.e., a phenolic polyether, andhave a number average molecular weight of generally about 2000 to about10,000.

There are two major pulping processes which promote lignin solubility,each using a different approach. In sulfite processes, the ligninmolecule is attacked by sulfonate anions generally in the presence ofsodium, ammonium, magnesium or calcium cations and at varying pH valuesto produce a range of pulps with varying lignin and hemicellulosecontents. The lignin molecule in this process becomes sulfonated andthus water soluble. Alternatively, in alkaline processes, the ligninmolecule is depolymerized by alkaline hydrolysis of the ether bondsbetween the aromatic units.

Lignosulfonate products are generally produced from wood by the acidbisulfite pulping process and the kraft process. In the acid sulfitepulping process, the lignin in, for example, wood chips is subjected toreaction with an aqueous bisulfite salt at elevated temperature andpressure. During the process, the lignin is rendered water-soluble by acombination of depolymerization and sulfonation. Both cleavage andsulfonation occur almost entirely at positions immediately adjacent tothe aromatic rings. Cleavage of this carbon-oxygen bond destroys one ofthe linkages common to both hardwood and softwood lignin.

The resulting lignin sulfonate is dissolved in the spent sulfite pulpingliquor along with a variety of carbohydrate compounds which areprimarily formed by degradation of the hemicellulose components of wood.The chemical composition of hemicellulose varies considerably withspecies of tree, even within the general categories of hardwoods andsoftwoods. The degradation products, therefore, also vary widely and caninclude glucose, mannose, galactose, xylose, arabinose and rhamnose inproportions which are determined largely by the wood source. Thesesugars usually account for 20-25% of the total spent sulfite liquorsolids. In addition, ash can be present in the liquor solids.

In sulfite pulping, generally up to about one-half of the coniferylbuilding units of the lignin molecule add sulfonate groups with varyingease. The locations of the attacks are generally the highly activebenzyl alcohol or benzyl ether groups of the lignin. These oxygencontaining groupings on the carbon adjacent to the aromatic ring arevery labile and are substituted in the pulping process by the highlypolar sulfonate groups. If the benzyl alcohol or ether is attached to afree phenolic unit, a sulfonate group is more readily introduced thanwhen the benzyl group is attached to a phenol ether. Sulfonationapparently also occurs on side chain carbons adjacent to carbonylgroups. Thus, through addition of solvating groups to the high polymerlignin and through low order acid hydrolysis and splitting of the ligninmolecule, solution of the lignin is achieved.

Lignosulfonates are generally classified as polydisperse macromolecularpolymers with molecular weights ranging from several hundred to morethan one hundred thousand. The phenylpropane structural units oflignosulfonates can be linked together in many different patterns bycarbon-carbon and ether linkages. Most of the sulfonate groups inlignosulfonates are thought to be joined to the alpha carbons of theside chain, with about one sulfonate radical for two phenylpropaneunits. Primary hydroxyl groups are found on many of the phenylpropaneunits while others have various carbonyl groups.

Lignosulfonates from the sulfite process can generally have a weightaverage molecular weight up to about 100,000. The calcium lignosulfonatecan be used as starting materials for other products due to the easewith which the calcium cation may be replaced with other cations to formthe appropriate soluble sulfate salts, such as sodium, ammonium andpotassium.

The other basic process to solubilize lignin is the alkaline pulpingprocesses. The most predominate lignin interlinkage is the beta ethertype, and this is cleaved by alkali to form smaller molecular sizephenols which tend to dissolve in water as the sodium phenolate salts.In phenyl coumarin type interlinkages, alkali attack frees the phenolicgroup for solubilizing salt formation, but concurrent formaldehyde lossfrom the side chain can produce a double bond between the two benzenerings to form phenolic stilbene portions in the alkali lignin.

In the kraft process, pulping liquor which contains from about 20 toabout 30 wt % sodium sulfide in a mixture with sodium hydroxide is used.Whereas, sodium hydroxide alone will depolymerize the lignin to solubleform, the hydroxide can also split the ether groups of the woodcarbohydrates causing their undesired dissolution. A sodiumhydroxide-sodium sulfite mixture is generally more effective inachieving continued lignin dissolution while having comparable effectson the carbohydrate dissolution. Apparently, sulfide not only promotesmore rapid splitting of the lignin ether groups, but introduction ofsulfur in the benzyl alcohol position may inhibit concurrentpolymerizing reactions.

The location of the alkaline attack on the native lignin generallyresults in the ether groups being split to form smaller molecular sizefree phenols. Typically about 5 to 10% of the lignin can be decomposedall the way down to monomeric phenols in the liquor, while the remainderis solubilized as higher molecular weight portions of the gross ligninmolecule. The potential ether split and loss of formaldehyde can producestilbene type structures. Comparable dehydration and formaldehyde losscan produce unsaturated ethers. In addition, carboxyl groups are alsofound in kraft lignin.

In alkaline hydrolysis, the phenolic group in the lignin molecule aregenerally doubled so that they are present on a majority of the units.

By proper two-stage acidification, coagulation and purification, therecan be obtained a reproducible kraft lignin from pine black liquor witha structure and number average molecular weight approximately about 2000to about 12,000 and a weight average molecular weight of about 2500 toabout 10,000. Based upon the mode of alkaline attack, a generalizedstructure can be designated as a plurality of aromatic units aspolyelectrolyte with phenolic groups, carboxyl groups, keto groups,aliphatic hydroxyl, and double bonds.

The processed lignin can be further processed to modify variousproperties of the lignin such as solubility in an aqueous medium, forexample, by substituent group modifications such as sulfonic, hydroxyl,polyhydroxyl and further reactions with polyhydroxy aromatic compounds,particularly catechol containing compounds. Such modifications,including examples as set forth above, are included within the scope ofthis invention.

Lignin derived products can undergo physical and chemical modificationby modification of sulfite liquor, sulfonated lignin, and kraft lignin.Depending on the optimum properties required, lignin derived products,including lignosulfonates, can be processed by one or more methodsincluding conversion to other salts, polymerization, classification ofmolecular weights, and oxidation-reduction of macromolecules. Thesolubility, absorption, electrolytic, and complexing characteristics ofsuch products can be modified based upon their molecular structure shapeand size, i.e., the type, quantity and location of functional groupsincluding sulfonic, sulfonate, sodium sulfonate, hydroxyl, poly hydroxyincluding di hydroxy benzene such as catechol, carbonyl, methoxy,carboxyl and chloride.

As set forth above, the preferred lignin derived products havingortho-quinone functionality are those having water solubilizing groups,particularly sulfonate, carboxylate, phenolate groups and the like whichenhance the solubility characteristics of such components particularlyat alkaline pH. In addition, it is preferred to optimize the amount ofortho-quinone functionality in the lignin containing component,preferably during processing such as during the sulfite or kraft pulpingprocess. During such processing, catechol functionality is believed tobe introduced by demethylation during the depolymerization and/orhydrolysis and other reactions of the lignin raw material. The formationof catechol functionality is believed to be enhanced by both temperatureand alkaline pH particularly at increased process severities. As setforth above, the lignin containing component can be further reacted toenhance the formation of catechol functionality. The catecholfunctionality can be converted to the ortho-quinone functionality using,for example, an active oxygen species, such as oxygen. As used herein,the term plant derived aromatic containing components includes bothcomponents having ortho-quinone functionality and/or catecholfunctionality which can be converted to ortho quinone functionality,preferably under the in situ and external regeneration processconditions of this invention. In addition, various substituent groupscan be introduced onto the catechol functionality group in order tomodify the oxidation potential and regeneration of the reducedortho-quinone functionality for overall effectiveness in the chemicalmodification of the hydrocarbon. In general, substituents on the quinonenucleus such as halogens particularly chloride, CN, So₃ Na in generalraise the potential of the ortho-quinone functionality, whereas alkyl,i.e., methyl, methoxy, hydroxy, and various amine and alkyl substitutedamine groups in general decrease the oxidation potential. As set forthabove, the optimum oxidation potential and the chemical modificationand/or oxidizing power of the ortho-quinone component is a function ofthe hydrocarbon, the process conditions particularly the pH, and theregeneration of the ortho-quinone component, whether such regenerationbe in situ such as when the ortho-quinone component is utilized incatalytic amounts or when larger amounts of the ortho-quinone componentare utilized. The ortho-quinone component can be regenerated, forexample, externally and recycled to the process. In general, it ispreferred to have an oxidation potential of the ortho-quinonefunctionality which allows for reasonable process efficiencies, i.e.,chemical modification of the hydrocarbons, so as to improve overallcrude oil liberation and to provide ease of regeneration for thecontinued chemical modification of the hydrocarbons by in situ and/orexternal regeneration.

Typical examples of lignin derived products which are suitable toprovide the o-quinone oxidants of this invention are, for example, thetreated or untreated spent liquors (i.e., containing the desiredeffluent lignin product solids) obtained from wood or other plantconversion, for example, the waste pulp liquor, or modified ligninproducts, such as by pyrolysis, reduction modification or ozonation ofthe aforementioned lignin individual products including spent liquors.The alkaline oxidized, hydrolyzed, partially desulfonated andsubsequently resulfonated lignosulfonates are also suitable.

Certain of these lignin containing components are obtained in wastepulping liquors derived from softwood and hardwood starting materials.Lignin containing components may be additionally sulfonated orsulfomethylated.

Other lignin containing products are the ozonated lignosulfonatesobtained from ozonation of the aforementioned ligno products, includingtreated or untreated spent liquors. In addition, purified lignincontaining products from which the sugars and other saccharideconstituents have been partially or totally removed such as byfermentation or, additionally, inorganic constituents have also beenpartially or totally removed are also useful.

As a further alternative, the lignin containing components may be one ofthe desulfonated lignosulfonates (including substantially purelignosulfonate compositions) which are generally obtained bycatalytic--frequently alkaline--oxidation processes conducted underconditions of high temperature and pressure, oftentimes withaccompanying hydrolysis.

As set forth above, further modification of the lignin derived productsare included within the scope of this invention and include the reactionof the foregoing lignin containing product materials with, for example,a halide, a halocarboxlyic acid or a sulfonating agent. In addition,further reactions can include one or more combinations of alkoxylation,sulfation, alkoxysulfation, alkylation or sulfomethylation. Any suitablesulfonation reagents may be used for sulfonation reaction. When straightsulfonation is desired, it is advantageously accomplished with an alkalimetal (such as sodium) sulfite or sulfur dioxide. Sulfoalkylation can beaccomplished with mixtures of an appropriate lower alkyl aldehyde and abisulfite.

Other lignin containing compounds which may be used in the practice ofthis invention are the derivatives of an oxidized, partiallydesulfonated lignosulfonate obtained in the spent oxidized liquor from adilute vanillin oxidized softwood or hardwood, spent sulfite liquor byacidification prior to vanillin extraction with an organic solvent andwhich can be further treated with, for example, sodium bisulfite and analdehyde, preferably formaldehyde, at elevated temperature tosulfoalkylate, and/or sulfomethlate, the desulfonated lignosulfonatemolecules.

Tannins occur in many plants and are in general separated by extraction.A typical example of tannin compound includes tree bark extract such asquebracho, hemlock and redwood extracts. The tannins are aromatic andare obtained from various plants and trees. Particularly preferredtannins are the condensed tannins which have catechol functionality,i.e., the catechol tannins which can generate and/or be converted toortho-quinone functionality.

As set forth above, the activity/regeneration of the o-quinonecontaining component can be affected by the pH of the aqueouscomposition employed in the present contacting step. Some activity ofthe o-quinone component may have to be sacrificed because of the pH ofthe aqueous composition during the contacting, which pH may be preferredfor various other processing reasons. The particular pH employed canalso affect the salt form of the o-quinone containing componentemployed, and such salts are o-quinone containing components within thescope of this invention.

As set forth above, the ortho-quinone containing components areeffective in a catalytic and/or promoting amount and/or chemicalmodifying, particularly in the presence of an additional active oxidantspecies such as oxygen, and such combination of component plusadditional oxidant allows the ortho-quinone containing component tocycle between an ortho-quinone functionality and a reduced catecholfunctionality. Thus, the ortho-quinone containing component can interactwith the hydrocarbon followed by regeneration, i.e., reoxidation of thecatechol functionality. After regeneration, the ortho-quinonefunctionality can further interact with the hydrocarbon. Thus theability to rapidly cycle between the ortho-quinone and catechol statesproduces a cycling component which can oxidize and be regenerated,thereby producing a series of oxidations/regenerations during contactingof the hydrocarbon. As set forth above, the ortho-quinone containingcomponent can be modified such as through substituent groups on thearomatic ring to optimize activity for both oxidation and regeneration,i.e., effective oxidation of the hydrocarbon with effectiveregeneration, preferably rapid regeneration. The optimization providesfor overall improved process effectiveness. Thus substituant groups suchas methoxy, sulfonate, hydroxy, chloride and cyanide can be used tomodify and enhance the overall oxidation regeneration effectiveness ofthe ortho-quinone containing components. Thus, it is preferred that theortho-quinone containing component cycle rapidly and produce a number ofcycles, for example at least about 4 cycles and generally from about 5cycles up to about 1000 cycles or more or up to about 100 cycles, thenumber of cycles in general being such number which effectively allowsfor an improvement in crude oil. The number of cycles in general will bea function of the crude oil, reservoir characteristics and remainingoriginal oil in place, the concentration of the ortho-quinone containingcomponent, as well as other impurities and components in the reservoirwhich may be susceptible to oxidation. By the term "cycle" is meant asingle oxidation regeneration cycle, commonly referred to in promotercatalyst terms as "one turnover."

The specific amount of the o-quinone containing component employed mayvary over a wide range and depends, for example, on the crude oil and/orthe o-quinone containing component employed, and on the degree ofoxidation desired. The weight percent of o-quinone functionality, basedupon the molecular weight of the ortho-quinone component, can vary overa wide range and in general represents a weight percent of from at leastabout 1 weight percent to about 40 weight percent of the weight of theortho-quinone containing component, i.e., for those compounds containingortho-quinone functionality, more preferably from at least about 2 toabout 30 weight percent and still more preferably from at least about 5weight percent to about 25 weight percent. By ortho-quinonefunctionality is meant an ortho-quinone functionality having a molecularweight of about 108 and the relationship of that molecular weight from aweight percent standpoint to the total molecular weight of the compound.For example, for certain components the total molecular weight can berepresented by the total molecular weight of the phenyl propane units,including substituents or such phenyl propane units. Since theortho-quinone containing components in general will be mixtures, theabove preferred ranges apply to the individual ortho-quinone containingcomponents within the mixture. Preferred molecular weight ranges arefrom about 1500 to about 75,000, more preferably from about 2000 toabout 10,000 and still more preferably from about 2000 to about 6000.

In certain embodiments, preferred concentrations of the ortho-quinonecontaining component are in the range of about 0.01 to about 4%, morepreferably from about 0.05 to about 2% by weight based upon the aqueouscomposition employed in the contacting, calculated as o-quinonecontaining component. It is generally convenient to provide theo-quinone containing compound in combination with, preferably insolution in, the aqueous composition used in the contacting step. As setforth above, it is preferred that the ortho-quinone containing componentbe present in an effective catalytic and/or promoting amount,particularly within the ranges set forth above. In addition, as setforth above, it is preferred that the ortho-quinone containing componentbe water soluble at the concentration and conditions at which it iseffective for carrying out the process of this invention.

The o-quinone containing component can be added to the contacting stepand/or can be formed in situ prior to or in the course of thecontacting.

The present contacting preferably takes place in the presence of anaqueous liquid medium or composition. The ortho-quinone containingcomponent, which is preferably soluble in the aqueous medium, may beadded to the aqueous medium prior to the contacting. Any suitable,aqueous medium can be employed in the present process. The pH of theaqueous medium may vary and in general a neutral or basic medium,preferably a basic or alkaline medium can be employed depending, forexample, on the reservoir being treated, the specific ortho-quinonecontaining component being employed, and the presence or absence ofother components or entities such as soluble metals during thecontacting. Preferably, the pH of the aqueous composition is in therange of about 7 to about 13, preferably from about 9 to about 13 and,still more preferably, from about 10 to about 12. The pH of the aqueousmedium may be adjusted or maintained, e.g., during the contacting step,for example, by adding acid and/or base.

The aqueous medium comprises water, preferably a major amount of water.The medium is preferably substantially free of ions and other entitieswhich have a substantial detrimental effect on the present process.Various bases or combination of bases may be included in, or added to,the medium to provide the desired pH. For example, alkali metalhydroxides, sodium and potassium, alkaline earth metal hydroxides,silicates, metal salts which decompose (in the aqueous medium) to formsuch bases, their corresponding carbonates, preferably sodium carbonate,mixtures thereof and the like may be employed. It is preferred to use anhydroxide or silicate as the base, preferably sodium hydroxide or sodiumortho silicate. The quantity and composition of the aqueous medium maybe selected in accordance with the requirements of any given reservoirto be treated and as may be found advantageous for any given modeapplying the present process in practice. In carrying out the presentprocess, one or more surfactants, polymers and/or metal catalysts can beincluded in, e.g., added to, the aqueous composition (in addition to theortho-quinone containing components) to further enhance rates and/oryields. Examples of such agents include hydrocarbon sulfonates,lignosulfonates, alkyl substituted succinic anhydrides, alcoholethoxylates and the like. Typical examples of metal oxidation catalystsare iron, copper, cobalt, vanadium, and manganese components which aresoluble in catalytically effective amounts in an aqueous medium,preferably selected from iron complexes with ligands, copper complexeswith ligands, vanadium components with ligands, manganese componentswith ligands, and mixtures thereof.

The amount of ortho-quinone containing components employed may varywidely provided that such amount is effective to function as describedherein. Such ortho-quinone containing components are preferably presentduring said contacting in an amount less than about 5%, more preferablyin the range of about 0.01% to about 4% by weight, and still morepreferably from about 0.05% to about 2%, calculated as o-quinonecontaining material, based on the amount of ore present and/or liquidpresent during contacting such as a solution used in an agitated leachor during a vat or heap leach. One of the substantial advantages of thepresent process is that large amounts of ortho-quinone containingcomponents are not required although adjustments can be made dependingon the various reservoir crude oil characteristics. Thus, in order toreduce costs still further while achieving benefits of the presentinvention, low concentrations of such materials are preferably selected.

The present contacting can be conducted in the presence of at least oneadditional active oxidant species other than the ortho-quinonecontaining component. The oxidant is present in an amount effective todo at least one of the following: maintain or form the ortho-quinonecontaining component, or produce or regenerate at least a portion of theortho-quinone containing component. The oxidant or oxidants may bepresent during the contacting step and/or during a separate step to formand/or regenerate the ortho-quinone containing component. Any suitableoxidant capable of performing one or more of the above-noted functionsmay be employed. The oxidant is preferably selected from the groupconsisting of molecular oxygen (e.g. in the form of air, dilute orenriched air, or other mixtures with nitrogen or carbon dioxide), singleoxygen, ozone, inorganic oxidant components containing oxygen and atleast one second metal and mixtures thereof. More preferably, theoxidant is selected from the group consisting of molecular oxygen,oxidant components containing oxygen and at least one second metal andmixtures thereof. Still more preferably, the oxidant is oxygen. Theoxidant can involve a mixture of oxidants such as an oxidant componentcontaining oxygen and at least one second metal, and molecular oxygen inan amount effective to maintain the ortho-quinone containing componentin the desired oxidized state or in the case of a reducible metaloxidant, to reoxidize such oxidant by, for example, molecular oxygen.Care should be exercised to avoid large excesses of the oxidant to as tominimize reactions that could solubilize deleterious elements.

By reducible metal oxidant is meant a metal component preferablymanganese which is capable of being chemically reduced at the conditionsof the present contacting. Preferably, metal oxidant includes manganese,more preferably a major amount of manganese, in at least one of the 3+and 4+ oxidation states. Particularly useful metal oxidants includemanganese dioxide, i.e., MnO₂, soluble manganese in the (3+) oxidationstate and mixtures thereof. The metal oxidant can be provided from anysuitable source, such as manganese halide and the like. The manganesecomponent originally present may be subjected to oxidation, e.g., bycontact with air and/or other manganese oxidant in the presence of base,in order to obtain and/or regenerate the presently useful metal oxide.The amount employed may vary over a wide range depending on, forexample, the specific metal oxidant being employed, what ortho-quinonecomponent is being used, what, if any, oxidant is being used, thespecific subterranean hydrocarbon-bearing reservoir being treated, andthe type and degree of chemical modification desired. Preferably, theamount of metal oxidant included in the present contacting step issufficient to maintain the desired amount of ortho-quinone oxidationstate during the contacting. Substantial excesses of metal oxidantshould be avoided since such excesses may result in material separationand handling problems, and may even result in reduced recovery ofhydrocarbons. In one embodiment, the reducible manganese component orcomponents are substantially soluble in the liquid medium at thecontacting conditions. Such substantially soluble manganese componentsare preferably selected form manganese ligand (3+) complexes. Aparticularly preferred oxidant comprises a mixture of molecular oxygenwith carbon dioxide in an amount effective to promote the molecularoxygen access to and contact with the hydrocarbons in the reservoir. Theuse of carbon dioxide has been found to enhance the chemicalmodification, e.g., oxidation, of the component or components of theoxidation, of the component or components of the hydrocarbon in thereservoir. Although carbon dioxide may be used alone, i.e.,substantially without an oxidant, it is preferably employed with anoxidant, and more preferably with molecular oxygen. When used withmolecular oxygen, the carbon dioxide is preferably present in an amountin the range of about 1.0 to about 1000 moles of carbon dioxide per moleof molecular oxygen. Care should be exercised to avoid using carbondioxide in amounts which substantially detrimentally affect the pH ofthe contacting liquid medium, e.g., reduce the pH of the liquid mediumbelow the desired level of solubility useful for plant derived aromaticcontaining component hydrocarbon modification, e.g., oxidation,activity.

The present contacting results in at least a portion of theortho-quinone containing component being chemically reduced to form areduced catechol containing component. This reduced component can exitthe contacting zone and be used on a once-through basis, or may beregenerated to an ortho-quinone containing component as set forth above,in situ or externally and recycled to the reservoir. In the case of aonce-through basis, it is preferred to minimize the amount of reducedcomponent exiting with the produced water and crude oil. Suchregeneration can be done by oxidizing the reduced component or withmolecular oxygen, in situ or external, at ambient and/or elevatedtemperatures to convert the reduced component to an ortho-quinonecontaining component.

The amount of oxidant employed in the present invention is chosen tofacilitate the desired functioning of the present contacting step.Without limiting the invention to any specific theory or mechanism ofoperation, it may be postulated that when oxidant is employed suchoxidant acts in conjunction with the ortho-quinone containing componentto chemically modify at least a portion of the hydrocarbon. Although theortho-quinone containing component takes an active part in the oxidationand recovery functioning, when oxidant is employed, such ortho-quinonecontaining component preferably acts as a catalyst or promoter and maybe, and preferably is, used more than once in the present contactingstep, e.g., is recycled to the present contacting step or is employed tocontact more than one increment of the oil in place.

The amount of oxidant employed preferably acts to facilitate the desiredoxidation of the reduced ortho-quinone containing component. Thespecific amount of oxidant employed varies depending on many factors,for example, the reservoir being treated, the specific ortho-quinonecontaining component and oxidant being employed, and the specific degreeof oxidation. Preferably, the amount of oxidant employed in the presentcontacting step should be sufficient to provide the chemicalmodification to the desired degree. Substantial excesses of additionaloxidant should be avoided since such excesses may result in reducedrecovery of the desired crude oil.

Although one or more of the oxidants may be utilized in a separateoxidation or regeneration step, it is preferred that such oxidants, andin particular oxygen, be present and effective during the contactingstep of the present invention.

One important feature of the present invention is that it may beeffectively practiced in the presence of brine which is often present insubterranean reservoirs, for example, after conventional water flooding.Thus, no "special" pretreatment of the reservoir is needed to employ thepresent process. In addition, the combination of brine and ortho-quinonecomponent can improve overall process effectiveness, such as reactivity,in the chemical modification of hydrocarbons. Thus, increased yields ofhydrocarbons can be recovered from reservoirs whether they have or havenot been previously water flooded and/or subjected to one or more otherEOR processes. In addition, in certain instances, the present processmay be advantageously used on a reservoir where primary recoveryprocessing has not been employed.

Any suitable drive fluid may be used in the present process incombination with the liquid medium. For example, the drive fluid may beselected from the group consisting of methane, ethane, propane, naturalgas, nitrogen, air, combustion flue gas, carbon dioxide, water, brine,and mixtures thereof. In one embodiment, the drive fluid is preferablyan aqueous composition. The drive fluid preferably includes a source ofoxygen in an amount effective to provide at least a portion of theoxidant, as described herein. The choice of a specific drive fluid foruse in the present invention depends on various factors, for example,the specific liquid medium being used, and the specific reservoir andreservoir conditions to be encountered. The amount of drive fluid issuch to urge or push the liquid medium toward the production means,e.g., production well or wells. The amount of drive fluid injected mayrange up to 100% or more of the reservoir or reservoir pre volume, basedon the volume of the drive fluid at the conditions present in thereservoir reservoir. The rate of drive fluid injection into thereservoir or reservoir is preferably such that the liquid medium sweepsor moves through the reservoir or reservoir at a substantially constantrate, i.e., distance per unit time.

It is preferred that the liquid medium including the plant derivedaromatic containing component, etc., noted herein, may be injected intothe reservoir in slugs, for example, alternating liquid medium and/orpolymer drive/pusher slugs. The amounts of liquid medium and drive fluidinjected into the reservoir may vary widely, depending on variousfactors, provided that such amounts and proportions act to provide forhydrocarbon recovery. If the liquid medium is injected as slugs, thesize of the individual slugs of liquid medium injected preferably rangeup to about 10%, more preferably up to about 50%, of the reservoir porevolume.

The conditions at which the present contacting in the subterraneanreservoir occurs may vary widely. In certain EOR processingapplications, it may not be possible to effectively control thetemperature and/or pressure of the subterranean reservoir during thecontacting step and/or to effectively control the time during which thecontacting occurs.

The present process provides for substantial hydrocarbon recoverywithout requiring the use of relatively expensive surfactants, such asthose used and/or proposed for chemical flooding. Also, substantially noadditional hydrocarbon need be injected. Thus, the present processinvolves less cost and may have improved effectiveness at elevatedreservoir temperatures relative to process using chemical floodingprocess. In certain applications, the injection or one or moresurfactants, polymers or foams, such as those conventionally used in EORprocessing, may have a beneficial effect on the recovery of hydrocarbonsin the present invention.

The following non-limiting examples illustrate certain of the advantagesof the present invention.

EXAMPLE 1

A crude petroleum bearing, porous reservoir is produced, usingconventional primary recovery methods, until it is determined thatenhanced oil recovery is needed to effectively and economically producethe reservoir further. Injection wells into the reservoir arestrategically located, in a conventional manner, relative to theproducing wells so that fluid injected in the injection wells would tendto sweep crude petroleum remaining in the reservoir toward theproduction wells for recovery.

Seawater (brine)is injected into the reservoir through the injectionwells. A quantity of crude petroleum is recovered. This waterflood/crudepetroleum recovery continues until it is determined that additionalenhanced oil recovery is needed to effectively and economically producethe reservoir further.

A combination of brine, sodium lignosulfonate having ortho-quinonefunctionality, sufficient sodium hydroxide to provide a pH of about 11is prepared. A concentration of 0.5% percent by weight of a sodiumlignosulphonate which had been produced by an acid bisulfite pulpingprocess is used. The sodium lignosulphonate had been processed to reducethe reducing sugar content to 0.1 wt/percent. The lignosulphonatefurther had the following chemical properties: 16.1% sodium, 0.5%calcium, 1.5% sulphate sulfur, 2.5% wt/pct non-sulphonate sulfur, 8.9%sulphonate sulfur, 11.4% total sulfur, 4.5% methoxy, and containedcatechol functionality. Prior to the addition of the sodiumlignosulphonate component, a 45 wt/percent aqueous solution of thesodium lignosulphonate was sparged with air at a temperature of 35° C.for a period of time of 30 minutes at a pH of 12 adjusted with sodiumhydroxide. The air sparging oxidized residual catechol functionality tothe ortho-quinone functionality. This combination is injected as a sluginto each of the injection wells, in amounts so that a total of about50% by volume of the pore space of the reservoir of the combination isinjected. This injection is followed by a mixture of polymer and water,optionally with air which is injected into each of the injection wells.The pH of the reservoir is controlled at about 11 by addition of sodiumhydroxide. A quantity of crude petroleum is economically recovered.

EXAMPLE 2

A crude petroleum-bearing, porous reservoir is produced, usingconventional primary recovery methods, until it is determined thatenhanced oil recovery is needed to effectively and economically producethe reservoir further. Injection wells into the reservoir arestrategically located, in a conventional manner, relative to theproducing wells so that fluid injected in the injection wells would tendto sweep crude petroleum remaining in the reservoir toward theproduction wells for recovery.

Seawater (brine)is injected into the reservoir through the injectionwells. A quantity of crude petroleum is recovered. This waterflood/crudepetroleum recovery continues until it is determined that additionalenhanced oil recovery is needed to effectively and economically producethe reservoir further.

A combination of brine, a sodium lignosulfonate as set forth in Example1, and sufficient sodium hydroxide to provide a pH of about 11 isinjected into the reservoir through the injection wells. Oxygen isdissolved in the aqueous medium to regenerate reduced ortho-quinonecontaining lignosulfonate. An initial high acid number of the petroleumin the reservoir is not required. The petroleum acids and other reactionby-products generated from the crude oil react with the alkalinecombination resulting in in situ generation of surfactants. Theoxidative cracking of petroleum in the reservoir may help change crudeoil mobility and recovery through oxidative viscosity reduction.

The injection of this alkaline combination is followed by a mixture ofpolymer and water which is injected into each of the injection wells.The pH of the reservoir is controlled at about 11 by addition of sodiumhydroxide. A quantity of crude petroleum is economically recovered.

The use of the present EOR process does not require that the porousreservoir be previously waterflooded or subjected to any other EORprocess. Good results are obtained if the present process is used on areservoir directly after primary recovery methods are used. In certainsituations, the present process may be employed without first using suchprimary production techniques.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

What is claimed is:
 1. A process for recovering hydrocarbons from asubterranean hydrocarbon-bearing reservoir comprising:contacting saidreservoir with at least one added plant derived aromatic componenthaving ortho-quinone functionality wherein the ortho-quinonefunctionality is present in the component in the range of from at leastabout 1 weight percent to about 40 weight percent of the total weight ofthe plant derived aromatic component and mixtures thereof, saidcontacting occuring at conditions effective to chemically modifycomponents of said hydrocarbons in said reservoir; and recoveringhydrocarbons from said reservoir.
 2. The process of claim 1 wherein theplant derived aromatic component is selected from the group consistingof lignin, tannin and mixtures thereof.
 3. The process of claim 2wherein the plant derived aromatic component is lignin.
 4. The processof claim 2 wherein the plant derived aromatic component has watersolubilizing groups selected from the group consisting of sulfonatesalts, phenolate salts, carboxylate salts and mixtures thereof.
 5. Theprocess of claim 4 wherein the plant derived aromatic component isselected from the group consisting of a sodium lignosulfonate, a sodiumlignin and mixtures thereof.
 6. The process of claim 5 wherein the plantderived aromatic component is a sodium lignosulfonate.
 7. The process ofclaim 3 wherein the ortho-quinone functionality is present in thecomponent in the range of from at least about 2 weight percent to about30 weight percent of the total weight of the plant derived aromaticunit.
 8. The process of claim 5 wherein the ortho-quinone functionalityis present in the component in the range of from at least about 2 weightpercent to about 30 weight percent of the total weight of the plantderived aromatic unit.
 9. The process of claim 1 wherein said plantderived aromatic component is present in an aqueous soluble catalyticamount to at least promote the oxidation of the hydrocarbons and anadditional oxidant is present to provide at least one of the following:(1) form and cycle said plant derived aromatic component betweenortho-quinone and catechol oxidation states and (2) cycle said plantderived aromatic component between ortho-quinone and catechol oxidationstates.
 10. The process of claim 6 wherein said plant derived aromaticcomponent is present in an aqueous soluble catalytic amount to at leastpromote the oxidation of the hydrocarbons and an additional oxidant ispresent to provide at least one of the following: (1) form and cyclesaid plant derived aromatic component between ortho-quinone and catecholoxidation states and (2) cycle said plant derived aromatic componentbetween ortho-quinone and catechol oxidation states.
 11. The process ofclaim 8 wherein said plant derived aromatic component is present in anaqueous soluble catalytic amount to at least promote the oxidation ofthe hydrocarbons and an additional oxidant is present to provide atleast one of the following: (1) form and cycle said plant derivedaromatic component between ortho-quinone and catechol oxidation statesand (2) cycle said plant derived aromatic component betweenortho-quinone and catechol oxidation states.
 12. The process of claim 9wherein the oxidant is oxygen and the contacting is in the presence ofan aqueous medium at a pH in the range of from about alkaline to about13.
 13. The process of claim 10 Wherein the oxidant is oxygen and thecontacting is in the presence of an aqueous medium at a pH in the rangeof from about alkaline to about
 13. 14. The process of claim 11 whereinthe oxidant is oxygen and the contacting is in the presence of anaqueous medium at a pH in the range of from about alkaline to about 13.15. The process of claim 4 wherein the salt is a sodium salt.
 16. Theprocess of claim 4 wherein the ortho-quinone functionality is present inthe component in the range of from at least about 2 weight/percent toabout 25 weight/percent of the weight of the plant derived aromaticcomponent.
 17. The process of claim 5 wherein the ortho-quinonefunctionality is present in the component in the range of from at leastabout 2 weight/percent to about 25 weight/percent of the weight of theplant derived aromatic component.
 18. The process of claim 6 wherein theortho-quinone functionality is present in the component in the range offrom at least about 2 weight/percent to about 25 weight/percent of theweight of the plant derived aromatic component.
 19. The process of claim13 wherein the ortho-quinone functionality is present in the componentin the range of from at least about 2 weight/percent to about 25weight/percent of the weight of the plant derived aromatic component.20. The process of claim 9 wherein the plant derived aromatic componentis lignin water solubilizing groups selected from the group consistingof sulfonate salts, phenolate salts, carboxylate salts and mixturesthereof and the salt is a sodium salt.